tmp/tmp5pzvgn83/{from.md → to.md}
RENAMED
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@@ -7,21 +7,23 @@ thread. A `thread` object uniquely represents a particular thread of
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execution. That representation may be transferred to other `thread`
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objects in such a way that no two `thread` objects simultaneously
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represent the same thread of execution. A thread of execution is
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*detached* when no `thread` object represents that thread. Objects of
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class `thread` can be in a state that does not represent a thread of
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execution.
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after default construction, after being moved from, or after a
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successful call to `detach` or `join`.
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``` cpp
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namespace std {
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class thread {
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public:
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// types:
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class id;
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-
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// construct/copy/destroy:
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thread() noexcept;
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template <class F, class... Args> explicit thread(F&& f, Args&&... args);
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~thread();
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@@ -73,19 +75,19 @@ namespace std {
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An object of type `thread::id` provides a unique identifier for each
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thread of execution and a single distinct value for all `thread` objects
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that do not represent a thread of execution ([[thread.thread.class]]).
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Each thread of execution has an associated `thread::id` object that is
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not equal to the `thread::id` object of any other thread of execution
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and that is not equal to the `thread::id` object of any `
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-
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`thread::id` shall be a trivially copyable class (Clause [[class]]).
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The library may reuse the value of a `thread::id` of a terminated thread
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that can no longer be joined.
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-
Relational operators allow `thread::id` objects to be used
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associative containers.
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``` cpp
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id() noexcept;
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```
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@@ -116,78 +118,80 @@ described in [[alg.sorting]].
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``` cpp
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bool operator<=(thread::id x, thread::id y) noexcept;
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```
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*Returns:* `!(y < x)`
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``` cpp
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bool operator>(thread::id x, thread::id y) noexcept;
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```
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*Returns:* `y < x`
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``` cpp
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bool operator>=(thread::id x, thread::id y) noexcept;
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```
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*Returns:* `!(x < y)`
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``` cpp
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template<class charT, class traits>
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basic_ostream<charT, traits>&
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operator<< (basic_ostream<charT, traits>&
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```
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*Effects:* Inserts an unspecified text representation of `id` into
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`out`. For two objects of type `thread::id` `x` and `y`, if `x == y` the
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`thread::id` objects shall have the same text representation and if
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`x != y` the `thread::id` objects shall have distinct text
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representations.
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*Returns:* `out`
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``` cpp
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template <> struct hash<thread::id>;
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```
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The
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template `hash` ([[unord.hash]]).
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#### `thread` constructors <a id="thread.thread.constr">[[thread.thread.constr]]</a>
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``` cpp
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thread() noexcept;
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```
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*Effects:* Constructs a `thread` object that does not represent a thread
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of execution.
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`get_id() == id()`
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``` cpp
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template <class F, class... Args> explicit thread(F&& f, Args&&... args);
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```
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*Requires:* `F` and each `Ti` in `Args` shall satisfy the
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`MoveConstructible` requirements.
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`std::forward<F>(f)), `*`DECAY_COPY`*`(std::forward<Args>(args))...)` ([[func.require]])
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shall be a valid expression.
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*Remarks:* This constructor shall not participate in overload resolution
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if `decay_t<F>` is the same type as `std::thread`.
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*Effects:* Constructs an object of type `thread`. The new thread of
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execution executes
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*`INVOKE`*`(`*`DECAY_COPY`*`(
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with the calls to *`DECAY_COPY`* being evaluated in the constructing
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thread. Any return value from this invocation is ignored.
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-
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-
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invocation of
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-
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-
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*Synchronization:* The completion of the invocation of the constructor
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synchronizes with the beginning of the invocation of the copy of `f`.
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*Postconditions:* `get_id() != id()`. `*this` represents the newly
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@@ -215,30 +219,31 @@ of `x.get_id()` prior to the start of construction.
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``` cpp
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~thread();
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```
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-
If `joinable()`, calls `
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-
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-
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-
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-
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-
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#### `thread` assignment <a id="thread.thread.assign">[[thread.thread.assign]]</a>
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``` cpp
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thread& operator=(thread&& x) noexcept;
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```
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-
*Effects:* If `joinable()`, calls `
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-
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*Postconditions:* `x.get_id() == id()` and `get_id()` returns the value
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of `x.get_id()` prior to the assignment.
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*Returns:* `*this`
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#### `thread` members <a id="thread.thread.member">[[thread.thread.member]]</a>
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``` cpp
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void swap(thread& x) noexcept;
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@@ -248,51 +253,49 @@ void swap(thread& x) noexcept;
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``` cpp
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bool joinable() const noexcept;
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```
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*Returns:* `get_id() != id()`
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``` cpp
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void join();
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```
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`joinable()` is `true`.
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-
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*Effects:* Blocks until the thread represented by `*this` has
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completed.
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*Synchronization:* The completion of the thread represented by `*this`
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synchronizes with ([[intro.multithread]]) the corresponding successful
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`join()` return.
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*Postconditions:* The thread represented by `*this` has completed.
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`get_id() == id()`.
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*Throws:* `system_error` when an exception is
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required ([[thread.req.exception]]).
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*Error conditions:*
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- `resource_deadlock_would_occur` — if deadlock is detected or
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`
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- `no_such_process` — if the thread is not valid.
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- `invalid_argument` — if the thread is not joinable.
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``` cpp
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void detach();
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```
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`joinable()` is `true`.
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-
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*Effects:* The thread represented by `*this` continues execution without
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the calling thread blocking. When `detach()` returns, `*this` no longer
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represents the possibly continuing thread of execution. When the thread
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previously represented by `*this` ends execution, the implementation
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shall release any owned resources.
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`get_id() == id()`.
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*Throws:* `system_error` when an exception is
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required ([[thread.req.exception]]).
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*Error conditions:*
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@@ -312,17 +315,21 @@ execution represented by `*this`.
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``` cpp
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unsigned hardware_concurrency() noexcept;
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```
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-
*Returns:* The number of hardware thread contexts.
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-
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-
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#### `thread` specialized algorithms <a id="thread.thread.algorithm">[[thread.thread.algorithm]]</a>
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``` cpp
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void swap(thread& x, thread& y) noexcept;
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```
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*Effects:* `x.swap(y)`
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execution. That representation may be transferred to other `thread`
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objects in such a way that no two `thread` objects simultaneously
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represent the same thread of execution. A thread of execution is
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*detached* when no `thread` object represents that thread. Objects of
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class `thread` can be in a state that does not represent a thread of
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execution.
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+
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+
[*Note 1*: A `thread` object does not represent a thread of execution
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after default construction, after being moved from, or after a
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+
successful call to `detach` or `join`. — *end note*]
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``` cpp
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namespace std {
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class thread {
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public:
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// types:
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class id;
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+
using native_handle_type = implementation-defined; // See~[thread.req.native]
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// construct/copy/destroy:
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thread() noexcept;
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template <class F, class... Args> explicit thread(F&& f, Args&&... args);
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~thread();
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An object of type `thread::id` provides a unique identifier for each
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thread of execution and a single distinct value for all `thread` objects
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that do not represent a thread of execution ([[thread.thread.class]]).
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Each thread of execution has an associated `thread::id` object that is
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not equal to the `thread::id` object of any other thread of execution
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+
and that is not equal to the `thread::id` object of any `thread` object
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that does not represent threads of execution.
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`thread::id` shall be a trivially copyable class (Clause [[class]]).
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The library may reuse the value of a `thread::id` of a terminated thread
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that can no longer be joined.
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+
[*Note 1*: Relational operators allow `thread::id` objects to be used
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+
as keys in associative containers. — *end note*]
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``` cpp
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id() noexcept;
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```
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``` cpp
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bool operator<=(thread::id x, thread::id y) noexcept;
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```
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+
*Returns:* `!(y < x)`.
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``` cpp
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bool operator>(thread::id x, thread::id y) noexcept;
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```
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+
*Returns:* `y < x`.
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``` cpp
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bool operator>=(thread::id x, thread::id y) noexcept;
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```
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+
*Returns:* `!(x < y)`.
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``` cpp
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template<class charT, class traits>
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basic_ostream<charT, traits>&
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+
operator<< (basic_ostream<charT, traits>& out, thread::id id);
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```
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*Effects:* Inserts an unspecified text representation of `id` into
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`out`. For two objects of type `thread::id` `x` and `y`, if `x == y` the
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`thread::id` objects shall have the same text representation and if
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| 146 |
`x != y` the `thread::id` objects shall have distinct text
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representations.
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+
*Returns:* `out`.
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``` cpp
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template <> struct hash<thread::id>;
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```
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+
The specialization is enabled ([[unord.hash]]).
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#### `thread` constructors <a id="thread.thread.constr">[[thread.thread.constr]]</a>
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``` cpp
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thread() noexcept;
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```
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*Effects:* Constructs a `thread` object that does not represent a thread
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of execution.
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+
*Postconditions:* `get_id() == id()`.
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``` cpp
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template <class F, class... Args> explicit thread(F&& f, Args&&... args);
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```
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*Requires:* `F` and each `Ti` in `Args` shall satisfy the
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+
`MoveConstructible` requirements.
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+
` `*`INVOKE`*`( `*`DECAY_COPY`*`( std::forward<F>(f)), `*`DECAY_COPY`*`( std::forward<Args>(args))...)` ([[func.require]])
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shall be a valid expression.
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*Remarks:* This constructor shall not participate in overload resolution
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if `decay_t<F>` is the same type as `std::thread`.
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*Effects:* Constructs an object of type `thread`. The new thread of
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execution executes
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+
` `*`INVOKE`*`( `*`DECAY_COPY`*`( std::forward<F>(f)), `*`DECAY_COPY`*`( std::forward<Args>(args))...)`
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with the calls to *`DECAY_COPY`* being evaluated in the constructing
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+
thread. Any return value from this invocation is ignored.
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+
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+
[*Note 1*: This implies that any exceptions not thrown from the
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+
invocation of the copy of `f` will be thrown in the constructing thread,
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+
not the new thread. — *end note*]
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+
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+
If the invocation of
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+
` `*`INVOKE`*`( `*`DECAY_COPY`*`( std::forward<F>(f)), `*`DECAY_COPY`*`( std::forward<Args>(args))...)`
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+
terminates with an uncaught exception, `terminate` shall be called.
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*Synchronization:* The completion of the invocation of the constructor
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synchronizes with the beginning of the invocation of the copy of `f`.
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*Postconditions:* `get_id() != id()`. `*this` represents the newly
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``` cpp
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~thread();
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```
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+
If `joinable()`, calls `terminate()`. Otherwise, has no effects.
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+
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+
[*Note 1*: Either implicitly detaching or joining a `joinable()` thread
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+
in its destructor could result in difficult to debug correctness (for
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+
detach) or performance (for join) bugs encountered only when an
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+
exception is thrown. Thus the programmer must ensure that the destructor
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+
is never executed while the thread is still joinable. — *end note*]
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#### `thread` assignment <a id="thread.thread.assign">[[thread.thread.assign]]</a>
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``` cpp
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| 235 |
thread& operator=(thread&& x) noexcept;
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```
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+
*Effects:* If `joinable()`, calls `terminate()`. Otherwise, assigns the
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| 239 |
+
state of `x` to `*this` and sets `x` to a default constructed state.
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| 241 |
*Postconditions:* `x.get_id() == id()` and `get_id()` returns the value
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| 242 |
of `x.get_id()` prior to the assignment.
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| 243 |
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+
*Returns:* `*this`.
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| 245 |
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| 246 |
#### `thread` members <a id="thread.thread.member">[[thread.thread.member]]</a>
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| 247 |
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| 248 |
``` cpp
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| 249 |
void swap(thread& x) noexcept;
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``` cpp
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bool joinable() const noexcept;
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| 256 |
```
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+
*Returns:* `get_id() != id()`.
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| 259 |
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| 260 |
``` cpp
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| 261 |
void join();
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| 262 |
```
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| 263 |
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*Effects:* Blocks until the thread represented by `*this` has
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| 265 |
completed.
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|
| 267 |
*Synchronization:* The completion of the thread represented by `*this`
|
| 268 |
synchronizes with ([[intro.multithread]]) the corresponding successful
|
| 269 |
+
`join()` return.
|
| 270 |
+
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| 271 |
+
[*Note 1*: Operations on `*this` are not synchronized. — *end note*]
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| 273 |
*Postconditions:* The thread represented by `*this` has completed.
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| 274 |
`get_id() == id()`.
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| 276 |
*Throws:* `system_error` when an exception is
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| 277 |
required ([[thread.req.exception]]).
|
| 278 |
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| 279 |
*Error conditions:*
|
| 280 |
|
| 281 |
- `resource_deadlock_would_occur` — if deadlock is detected or
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| 282 |
+
`get_id() == this_thread::get_id()`.
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| 283 |
- `no_such_process` — if the thread is not valid.
|
| 284 |
- `invalid_argument` — if the thread is not joinable.
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| 285 |
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``` cpp
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| 287 |
void detach();
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```
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*Effects:* The thread represented by `*this` continues execution without
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| 291 |
the calling thread blocking. When `detach()` returns, `*this` no longer
|
| 292 |
represents the possibly continuing thread of execution. When the thread
|
| 293 |
previously represented by `*this` ends execution, the implementation
|
| 294 |
shall release any owned resources.
|
| 295 |
|
| 296 |
+
*Postconditions:* `get_id() == id()`.
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| 297 |
|
| 298 |
*Throws:* `system_error` when an exception is
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| 299 |
required ([[thread.req.exception]]).
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| 300 |
|
| 301 |
*Error conditions:*
|
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|
|
| 315 |
|
| 316 |
``` cpp
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| 317 |
unsigned hardware_concurrency() noexcept;
|
| 318 |
```
|
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|
| 320 |
+
*Returns:* The number of hardware thread contexts.
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| 321 |
+
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| 322 |
+
[*Note 1*: This value should only be considered to be a
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| 323 |
+
hint. — *end note*]
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+
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+
If this value is not computable or well defined an implementation should
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+
return 0.
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| 328 |
#### `thread` specialized algorithms <a id="thread.thread.algorithm">[[thread.thread.algorithm]]</a>
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| 330 |
``` cpp
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| 331 |
void swap(thread& x, thread& y) noexcept;
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| 332 |
```
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+
*Effects:* As if by `x.swap(y)`.
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|